In a conventional process for accumulating pillow-type packaging bags in a linear arrangement, a guide member is provided upstream of the bags, and the procession of the packaging bags is controlled so as to be linearly shaped. For example, in the first conveyance apparatus disclosed in Patent Literature 1 (Japanese Laid-Open Patent Publication No. 2011-31989), guide members are provided to both sides of a horizontal part through which the packaging bags are horizontally conveyed, and the guide members inhibit a disturbance in the line of packaging bags.